Chemical composition, antioxidant activity and antimicrobial properties of propolis extracts from Greece and Cyprus

Chemical composition, antioxidant activity and in vitro antimicrobial activity of twelve propolis ethanolic extracts (PEE) from mainland Greece, Greek islands, and east Cyprus were determined. The PEE studied contained significant amounts of terpenes and/or flavonoids, anthraquinones – mainly emodin and chrysophanol – and low amounts of phenolic acids and their esters, presenting differences from typical European propolis, and similarities to East Mediterranean propolis. Simple polyphenols and terpenic acids content ranged between 11.9–373.5 and 7.23–286.5 mg/g of PEE, respectively, with anthraquinones representing the 1.3–28.9% of simple polyphenols. Despite differences in composition, the PEE samples exhibited significant antioxidant, antibacterial, and antifungal activities, affecting a wider spectrum of microorganisms than the food grade antibacterial nisin, and presenting lower or no activity against several Lactobacillus strains. The presence of significant amounts of terpenoids seemed to enhance the antimicrobial activity of PEE. The conclusion, given the non-toxic and natural origin of PEE, is that, besides their potential pharmaceutical and nutraceutical value, propolis balsams from Greece and Cyprus are attractive candidates for use as natural antioxidant and microbicidal additives in food systems, especially those containing lactic acid bacteria.